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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-45551

MEDIUM · 5.1 CVSS v4.0 Published 2026-05-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
55/100
Remediation priority · Elevated
Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Group-Office is an enterprise customer relationship management and groupware tool. Prior to 26.0.25, 25.0.100, and 6.8.165, GroupOffice allows authenticated users to persist arbitrary legacy settings for any user_id via index.php?r=core/saveSetting. A separate client-side sink in the email module injects the email_font_size setting directly into JavaScript without escaping. By combining these two issues, any low-privileged authenticated user can overwrite an administrator's email_font_size setting with a JavaScript payload and trigger stored XSS in the administrator's browser when the GroupOffice web client loads views/Extjs3/modulescripts.php. This vulnerability is fixed in 26.0.25, 25.0.100, and 6.8.165.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Group-Office allows low-privileged authenticated users to exploit an IDOR vulnerability in index.php?r=core/saveSetting to overwrite arbitrary settings (like email_font_size) for any user. A client-side sink in the email module then injects this setting into JavaScript without escaping, causing stored XSS when administrators load views/Extjs3/modulescripts.php.

MitigationUpgrade to version 26.0.25, 25.0.100, or 6.8.165. Until then, restrict access to the saveSetting endpoint and monitor for suspicious setting modifications.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
Authentication
X
User interaction
P
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Group-Office version
    Locate the version file in your Group-Office installation (typically in /path/to/groupoffice/version.php or check the admin panel under System > Information). Compare the installed version number against the known fixed versions: 26.0.25, 25.0.100, or 6.8.165. Any version lower than these is potentially affected.
    Affected if Installed version is below 26.0.25, 25.0.100, or 6.8.165
  2. Verify email module is enabled
    Check the Group-Office modules configuration either through the administrative web interface (Modules section) or by examining the database table 'core_module' for an active email module entry.
    Affected if Email module is installed and enabled
  3. Inspect the email_font_size setting in database
    Query the database settings table (likely 'core_setting' or similar legacy settings table) for records where setting_name equals 'email_font_size'. Examine the setting_value field for any suspicious JavaScript code patterns such as <script, javascript:, onerror=, onload=, or similar XSS vectors.
    Affected if The email_font_size setting contains unsanitized JavaScript or HTML tags
  4. Check the vulnerable code in modulescripts.php
    Locate the file at views/Extjs3/modulescripts.php within the Group-Office web root. Search for the string 'email_font_size' and verify whether the value is being directly injected into JavaScript context without proper escaping (e.g., no htmlspecialchars, json_encode, or equivalent encoding).
    Affected if The setting value is echoed directly into JavaScript without encoding
  5. Test IDOR access to core/saveSetting endpoint
    Using an authenticated low-privilege account, attempt a POST request to index.php?r=core/saveSetting with parameters including a different user_id (such as an administrator) and a legacy setting name like 'email_font_size' with a test value containing harmless characters. Verify if the request succeeds without proper authorization checks.
    Affected if The endpoint allows modifying settings for user IDs different from the authenticated user

You are affected if your Group-Office version is below 26.0.25/25.0.100/6.8.165, the email module is enabled, and either the email_font_size setting contains malicious code in the database or the modulescripts.php file lacks output encoding for this setting.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to version 26.0.25, 25.0.100, or 6.8.165. Until then, restrict access to the saveSetting endpoint and monitor for suspicious setting modifications.

Recommended fix High confidence

Upgrade to 26.0.25, 25.0.100, or 6.8.165 depending on your current version line

  1. Identify the currently installed Group-Office version by checking the administration panel or version files
  2. Determine which version line (6.8.x, 25.x, or 26.x) the installation is running
  3. Download the appropriate fixed version from the official Group-Office source: 6.8.165, 25.0.100, or 26.0.25
  4. Backup the existing Group-Office installation directory and database before upgrading
  5. Stop the web server to prevent active sessions during the upgrade process
  6. Replace the existing Group-Office files with the new version
  7. Run any database migration scripts included in the upgrade package if required
  8. Restart the web server and verify Group-Office loads correctly
Caveat Review the official release notes for your version line to check for any breaking changes or required configuration updates

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,820
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45551 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data